Consider the markets for mobile and landline telephone service. Suppose that when the average income of residents of Plainville is $55,000 per year, the quantity demanded of landline telephone service is 12,500 and the quantity demanded of mobile service is 28,000. Suppose that when the price of mobile service falls from $120 to $100 per month, the quantity demanded of landline service decreases to 11,000. Suppose also that when the average income increases to $60,000, the quantity demanded of mobile service increases to 33,000.

1. Using the midpoint method, what is the income elasticity of demand for mobile service? Considering the income elasticity, what type of good is mobile telephone service?

2. Using the midpoint method, what is the cross price elasticity of demand for landline and mobile service? Considering the cross price elasticity of demand for mobile and landline telephone service, is the cross price elasticity of demand positive or negative and do the consumers of Plainville regard these goods as substitutes or complements?